Add boundary buffer to AnalysisJob model and feed it through to the data processing

[lydiascarf]

Criteria:

• NB_BOUNDARY_BUFFER is configured in the AnalysisJob model before being fed to the analysis script
• In the Django shell, you can look at a newly created AnalysisJob and confirm that it has the boundary buffer set in the model

Proposed implementation:

• Use NB_MAX_TRIP_DISTANCE as an example to add boundary buffer to the AnalysisJob model

[lydiascarf]

nevermind! we're just going to continue treating NB_MAX_TRIP_DISTANCE and NB_BOUNDARY_BUFFER as equivalent